High pressure valves, particularly those used in the chemical industry, are often subjected to extremely high pressure and temperature conditions. The seal rings used in certain types of such valves consequently may have a relatively short life and may have to be replaced at frequent intervals. One such valve is the so called "seatless" valve characterized by a plunger moving past an inner seal ring on closure to prevent valve clogging or plugging. In a conventional high pressure seatless valve, the inner and outer seal rings are maintained in resilient sealing engagement with the plunger and the valve body by means of a spring-loaded gland bearing against the outer seal. A sleeve extending between the inner and outer seal rings transmits the gland force to the inner seal ring.
When the seal rings of a conventional seatless valve require replacement, the valve must be completely disassembled, a laborious process which may take several days to complete. The plunger and gland must be removed to permit access to and removal of the outer seal ring, following which the sleeve and inner seal ring can be removed. Since the larger size valves may weigh several thousand pounds, disassembly in the field can be an ordeal. In some cases, the residue from fluids which have passed through the valves causes the valve parts to stick together, complicating disassembly and causing further delays in returning the valves to service.